Cholesterol vehicle in experimental atherosclerosis: X. Influence of specific saturated fatty acids

Abstract

The possible role of specific saturated fatty acids in the development of atherosclerosis in rabbits has been assessed. Special fats were prepared by randomizing corn oil with pure trilaurin (L), trimyristin (M), tripalmitin (P), and tristearin (S), yielding oils of similar iodine value (102 ± 2) but differing in the predominating saturated fatty acids. Rabbits were fed for 8 weeks on diets consisting of chow augmented with 2% cholesterol and 6% of fats L, M, P, and S. Other groups of rabbits were fed diets in which corn oil (CO) or randomized corn oil (R) were used as the cholesterol vehicle. In a series of four experiments with a cholesterol-containing diet, the four different saturated fats were more atherogenic than either native or randomized corn oil. The palmitic acid-rich fat (P) was somewhat more atherogenic than were the other special fats. This observation was also true when the atherogenicity of the various fats was expressed as a function of the degree of hypercholesteremia they induced. The aortic cholesterol ester was elevated in all six groups of rabbits (27–40% vs. 5% in normal rabbits) and could not be correlated with severity of atheromata; however, the average total cholesterol content of the thoracic aorta did correspond to the degree of atherosclerosis. Average serum cholesterol levels were lower in the special fat groups than they were in the rabbits fed corn oil. Possibly the presence in these diets of relatively large amounts of unsaturated fatty acids masks the specific hypercholesteremic effects of saturated fatty acids.